I’ve been wondering what teams use for their drive train.
We’re thinking of a regular tank drive or an X-drive, but we still haven’t talked much about it yet.
I think I included most of the practical drive trains in the poll, so if “Other” please specify 
Driving up ramps always seems to be the elephant in the room when it comes to X-drives. I think any x-drive this season will have to specialize in lifting and not being lifted. That being said, it seems like an x-drive would be perfect for maneuvering around the field. Mecanum drives have the issue of slowing down when strafing, so any mecanum drives used should probably focus on shooting Driver Control Loads. A non-holonomic drive is safe and simple, so that should be the norm in the early season.
Also, does a + Drive count as an H-drive?
I’ll count it as an X-Drive since it’s outside the middle.
You’re point on X-Drives is makes me reconsider some ideas. Thanks!
I think that H-Drives offer the best mobility and maneuverability, which will indubitably become the deciding factor of high level matches. Although some see H-Drives as wasting a motor (or in my team’s case 2), if the motor power on any robot is well utilized and all advantages are taken to ensure power efficiency is maximized, then it is the superior drive in terms efficiency, speed, and power.
I believe that an x drive offers the most mobility and allows for fast scoring since this year we have different parts of the field to score from. Additionally you can move diagonal which I see as a great advantage.
H-Drives can move diagonally
Correct me if I am wrong, but wouldn’t X-Drives make it harder for ramp compatibility?
I personally have a tank drive, but I believe that H-Drive would have the flexibility for ramps AND the mobility for collecting balls.
I think it is possible for ramps to be formatted so x drives can drive up. The real issue is the brute force needed for said robot to lift itself up but i think that could be achieved through engineering on the liftees part. these are important concepts that should be discussed early on so teams can designate whether they would like to become lifters or lifts
If you use an X Drive, would the force be inefficient? With the tank drive, the force is a direct forward (considering that you are entering the ramp perfectly), while climbing a ramp with an X Drive will give you less force due to the fact that your forces are being applied diagonally.
Also any slight deviation in your motors’ RPMs will cause your X Drive to potentially slide off the ramp.
Since we have the 12 motors rule this season, some teams might actually choose to go on the path of H-drive. It offers the advantages of a tank drive and a X-drive, and I can definitely see it being used by teams this year. Being mobile will definitely be important for avoiding blocker-bots and will also assist the driver in aiming. A H-drive is also much better for climbing ramps as compared to a X-drive, and still has the same abilities as a X-drive.
Personally I will be trying out this particular drive with my team, and we have hopes that the drive will work well (but then again we never know). The concept of the H-drive is good, but ultimately it will be just about how teams implement it to their robots and make the design work well with the rest of their robot.
Well since an x drive is 41.5% faster than a tank drive, that means the torque is inversely proportional to that speed advantage. so an x drive would be at a disadvantage for climbing up a ramp (which requires torque over speed). Furthermore the possibility of falling off the ramp is daunting. I agree that for this season H drives or Tank Drives would be best for any potential liftee
X drives aren’t exactly inefficient. The forces don’t cancel each other out as many people believe. X drives do have less pushing ability compared to drives with identical gearing and wheels parallel, although they are also faster by a ratio of 1:1.414 (root 2)
I can’t remember for sure, but someone on the forums gave a very good explanation for why that is (I believe it was Cody?). Basically, the rollers of the wheels let it slide in the direction of the other wheels (think about when two wheels drive and two wheels roll freely when driving diagonal). However, what it can effectively do is combine driving in both diagonal directions at the same time. So, when driving north, it drives simultaneously 1 unit northwest and one unit northeast, resulting in it travelling 1.414 units north. (I’m sorry if this makes no sense, I can try clarify doubts if you ask?)
Also X drives can go up inclines to an extent, for example at NZ toss up Nationals I had the third best (of three :p) X drives, all of which managed to get over the bump.
Here is the explanation from AURA for why Xs are faster:
http://www.aura.org.nz/archives/1137
We will probably have to run a few tests (ramp, pushing, etc) and determine the best drive from that, as there are a lot of factors coming up.
I am aware that X-drives can travel around the field more efficiently than a tank drive, but what I mean to ask is would it be better suited to use a tank drive since it has more concentrated force.
2114A’s Toss Up robot had a shifting X-Drive/Tank drive. Their robot had a pulling force of 4 lbs when using an X-Drive configuration, and have a pulling force of 5.6 lbs in tank drive configuration. The X-drive can surely travel faster, but tank drives seem to be better suited for ramps since you are only traveling one direction, thus having more “push.”
http://youtu.be/VpcXp7TV_FA <–2114A’s Toss Up Bot
I think the main consideration is going to be a weighing of cost/benefit depending on drive. X-drive has mobility (strafing) and speed but sacrifices torque. Tank drive has torque but average speed and (slightly) greater friction when turning. H-drive has average speed and torque but still can strafe at the cost of more motors. At the end its going to depend on individual team strategies as well as consideration on alliance strategies.
https://www.youtube.com/watch?v=MtzL2qg7z5A
So use a binary swerve drive and have the same mobility of an X-Drive and the same power as an H-Drive with no extra motor.
I mean no offense Complexist but by using that configuration you actually lose 2 motors. An H drive would be a better use of all resources available. The only instance where that would be useful this season is if there isn’t any space for the wheels in the center. Of course i could be wrong in some way and if so please correct me
How can you lose two motors when it is only necessary to use one to shift it if you don’t use pneumatics? With pneumatics no motors are lost and with 12 motors one is lost, but all four drive motors working together going any direction except for diagonals (which works against itself like an H-Drive or can be a crab drive) IMO makes up for that.
effectively creating a shifting drive train with only one motor would be extremely space consuming and complicated. if it was achieved that would be applauded. and what i meant by 2 motors lost with pneumatics is that you can only utilize 10 motors instead of 12. Its an exremely difficult scenario. And personally i have see dexterous 5 motor drives so i would chose to use that shifting motor instead in an H-drive config.
I personally think that pneumatics are WAY better than 12 motors given that the cortex isn’t built to handle 10 393’s let alone 12, and the number of tasks able to be performed with a well planned pneumatic system is far more than that of two extra motors. I’m not saying that pneumatics are ABSOLUTELY better than 12 motors, but two pistons can comfortably shift a fully variable crab drive that can run down to 30 psi and lower depending on the stress and still have air to spare for many more functions. At least in my experience, proper air management can easily outperform most 12 motor systems, but cost quickly becomes an issue. It’s not really a matter of better or worse overall, it’s about the efficient application of a system to a certain situation. 12 motors can definitely be better in some cases, but from all my experience, pneumatics win for most robots because at this point although they are super expensive pneumatics offer far more possibilities because they don’t stress the batteries and cortex and there is no piston limit.